Waze in iOS 18 when also using car GPS

Prior to iOS18, I could start a Waze trip in Carplay, then start the same trip using Hyundai's GPS system and both would work. I do this because I like the visuals of Waze with Traffic and easily see my ETA but Hyundai's GPS was the only one putting directions into my HUD. If I started the Hyundai's GPS first, it would stop once I started Waze, so I've been good about starting Waze first. After updating to iOS18 and the Waze up, now I can only have one of them running. I've seen somewhere that Carplay requires GPS apps to use the car's GPS and I'm wondering if that is what is causing the issue. I've not found any settings in Waze, Carplay or Hyundai to try to resolve this. Thoughts?